JPH064730U - Coupling member - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the ambient temperature changes, the connection and sticking relations of two or more members with different linear expansion coefficients should not shift. [Structure] At least one member when two or more members having different linear expansion coefficients, for example, an aluminum rotor and an iron yoke of a polygon mirror motor are partly connected and fixed by a connecting and fixing means such as a screw and a screw hole 20. A space 21 is provided in the vicinity of the coupling and fixing means 20 to enable the deformation of the mating member in the space, and even if a stress occurs between the coupled members due to a change in ambient temperature, the deformation in the space 21 occurs. Absorbs the displacement and relaxes the stress.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a joining member that joins two or more members having different linear expansion coefficients with a joining and fixing means. More specifically, the present invention relates to a connecting member suitable for use in a case where a cylindrical body having a bottom portion is double-fitted to be joined and fixed at the bottom portion.

[0002]

[Prior art]

 As an example of coupling two members having different linear expansion coefficients, for example, fixing a rotor 101 made of aluminum and a yoke 102 made of iron in a polygon mirror motor as shown in FIG.

The polygon mirror motor has been conventionally used as an optical scanning device for, for example, a laser beam printer or a facsimile, and is provided at the end of a cylindrical rotor 101 supported by a dynamic pressure air bearing 103. A boss portion 104 having a small diameter is provided, a polygon mirror 105 is mounted, and this is rotated at high speed. The rotor 101 is made of an aluminum alloy that can be easily cut, and the stator coil 106, the rotor magnet 107, and the like are arranged inside the rotor 101, and a motor 108 is formed coaxially with the dynamic pressure bearing 103. The dynamic pressure bearing 103 usually has a spiral dynamic pressure generating groove 109 formed on the outer peripheral surface of the rotor 101, and has a very narrow fixed bearing gap (usually several μm to several tens of μm) with the bearing member 110. ) Has been formed. Therefore, when a predetermined bearing gap cannot be accurately ensured between the rotor 101 and the bearing member 110, they come into contact with each other to generate frictional heat, and the contact portion is melted so that the shaft and the bearing are adhered. There is a risk of causing a phenomenon. Therefore, in order to manufacture the rotor 101 and the bearing member 110, sufficient roundness and squareness accuracy are required.

In such a polygon motor, conventionally, the iron yoke 102 is fixed to the rotor 101 by applying an adhesive to the entire inner peripheral surface 111 of the rotor 101 to adhere the yoke. However, when the rotor 101 is formed of an aluminum alloy, it is soft and therefore deformed relatively easily by the application of an external force, which makes it impossible to maintain the bearing gap. That is, the shrinkage force when the adhesive is cured is applied to the entire area of the rotor 101 and deforms the vicinity of the opening end of the rotor 101, which is relatively weak, and affects its accuracy (roundness / squareness). As a result, the yield of products has deteriorated.

Therefore, as shown in FIG. 5, the yoke 102 is formed into a bottomed cylindrical shape similar to the rotor 101, and the bottom portion 112 thereof is attached to the boss portion 104 of the rotor 101 with a screw 113 or an adhesive. I thought about making it scattered and fixing it like a spot.

[0006]

[Problems to be solved by the device]

 However, when the iron yoke 102 is attached to the aluminum rotor 101 with the screw 113, the yoke 102 is generally biased to one side as shown in FIG. That is, the yoke 102 having a diameter slightly smaller than that of the rotor 101 is in contact with the rotor inner peripheral surface 111 at at least one point and is fixed in that state. Then, in that state, the rotational balance of the entire rotary system including the polygon mirror 105 and the like is adjusted and balanced. Therefore, when the environmental temperature becomes considerably lower than during balance adjustment during transportation in winter, a relative displacement occurs between the rotor 101 having a large contraction amount and the yoke 102 having a small contraction amount. That is, as shown in FIG. 4 (B), when a stress caused by a difference in linear expansion coefficient is generated at the joint portion J due to a change in environmental temperature and becomes larger than the tightening friction resistance of the joint portion J. There is a problem that the coupling relationship between the two members 101 and 102 is deviated. Then, after that, when the operating environment temperature is kept in a certain state such as when using the product, as shown in FIG. 4C, the rotor 101 expands again and the position of the yoke 102 is displaced. It is left as it is. Therefore, the iron yoke 102 is displaced in the radial direction with respect to the aluminum rotor 101, and the center of gravity of the yoke 102 deviates from the rotation axis O of the rotor 101, and the rotational balance is lost. This is also the case when spot-wise fixing with an adhesive or the like, and the adhesive at the joint J where the stress exceeding the adhesive force is generated is destroyed and the bonding relation is disturbed.

An object of the present invention is to provide a joining member composed of two or more members having different linear expansion coefficients so that the joining relationship and the sticking relationship do not shift even if the environmental temperature changes to some extent.

[0008]

[Means for Solving the Problems]

 In order to achieve such an object, the present invention provides a connecting member in which two or more members having different linear expansion coefficients are partially connected and fixed by a connecting and fixing means, and a connecting member between the two or more members is provided in the vicinity of the connecting and fixing means. Space is intervening.

[0009]

[Action]

 Therefore, even if stress is generated between members with different linear expansion coefficients, which are connected and fixed in a spot due to linear expansion due to changes in ambient temperature, this stress is generated in the space near the bonding and fixing means. Absorbs the expansive deformation of the member.

For example, an example of a coupling structure of a rotor and a yoke of a polygon mirror motor is shown in FIG. When assembling the product, the rotor 2 and the yoke 19 are fixedly coupled and fixed as shown in FIG. 3 (A) without any deformation. When the temperature becomes low, the rotor 2 contracts relatively and the yoke 19 is tightened. However, since there is a space 21 near the connecting and fixing means 18 of the rotor 2 and the yoke 19, stress does not occur in this portion because the rotor 2 does not directly contact the yoke 19. The contact between the yoke 19 and the rotor 2 occurs at the end A of the space 21 axially farther away from the coupling and fixing means 18, that is, at a position where the coupling relationship between the rotor 2 and the yoke 19 is displaced and / or at a position far away from the direction. Therefore, the A portion of the yoke 19 is distorted and absorbs the stress, or the B portion of the rotor 2 side where the space 21 is provided is distorted and absorbs the stress, and is larger than the tightening frictional resistance of the joint portion J. The stress is not applied to the joint, that is, the joint of the two members is not displaced. After that, when the operating environment temperature returns to its original value, such as when using the product, the rotor 2 swells and restores the same state as the balance adjustment shown in FIG. 3A [see FIG. 3C].

[0011]

【Example】

 Hereinafter, the configuration of the present invention will be described in detail based on the embodiments shown in the drawings. This embodiment is applied to a combined structure of a rotor and a yoke of a polygon mirror motor used in an optical scanning device such as a laser printer.

FIG. 1 shows an embodiment of a polygon mirror motor to which the present invention is applied. This polygon mirror motor is composed of a polygon mirror 1 and a motor unit 3 that supports and rotates the polygon mirror 1. The motor unit 3 includes a cylindrical rotor 2 that supports the polygon mirror 1, a substantially cylindrical bearing member 5 that rotatably supports the rotor 2 by forming a dynamic pressure bearing 4 between the rotor 2 and the rotor 2. It is composed of a stator coil 9 fixed to the inner center pole 8 and a rotor magnet 10 fixed to the inner peripheral surface of the rotor 2, and is driven by, for example, a brushless control system. Further, the rotor 2 is floated in the thrust direction by a magnetic thrust bearing utilizing the attractive force of the pair of magnets 11 and 12 arranged between the center pole 8 and the rotor 2, while the dynamic pressure bearing is used. It is supported in the radial direction by the dynamic pressure generated in No. 4.

The rotor 2 has a bottomed cylindrical shape with a small diameter boss portion 13 penetrating the polygon mirror 1 at one end, and the polygon mirror 1 is mounted on the bottom portion around the boss portion 13. There is. The polygon mirror 1 is pressed and fixed to the rotor 2 by the elastic force of a corrugated spring 17 arranged between the polygon mirror 1 and the balance plate 16 which is fixed to the boss portion 13 of the rotor 2 with screws 18. A spiral groove 15 for generating a dynamic pressure is formed on the outer peripheral surface 14 of the rotor 2 by etching or the like, and is coated with a hard coating such as SiC composite plating. The balance plate 16 prevents the position of the center of gravity of the entire rotation system including the polygon mirror 1 from being displaced from the center axis of the rotor due to a processing error, an installation error when the polygon mirror 1 is attached to the rotor 2, and the like.

The bearing member 3 is also made of an aluminum alloy similarly to the rotor 2, and has a lubricating coating formed of lubricating alumite on the inner peripheral surface of the dynamic bearing surface. Of course, a hard coating may be applied to the bearing member side, and a lubricating coating may be applied to the rotor 2 side.

A cylindrical rotor magnet 10 is fixed inside the rotor 2 with a yoke 19 interposed therebetween. The yoke 19 is a bottomed cylindrical body, and a screw hole 20 into which a screw 18 as a coupling and fixing means is screwed is provided in a coupling and fixing region formed on the bottom of the yoke 19. It should be noted that the rotor magnet yoke 19 is fixed to the rotor 2 only in the combined and fixed area, and is not fixed in the other non-bonded and fixed areas. A space 21 is provided between the rotor 19 and the yoke 19 near the place where the screw 18 is connected. The space 21 is provided in a direction and / or a position where the fixed relationship between the yoke 19 and the rotor 2 due to the screw 18 is displaced when the environmental temperature changes. For example, a space 21 is provided on the inner peripheral surface side of the rotor around the screw 18, and the yoke 19 can be deformed in the radial direction. The shape of this space 21 is not particularly limited, but for example, a concave portion that makes one round around the inner peripheral surface of the rotor 2 is preferable. The end of this recess may be a step as shown in the figure, or may be a tapered shape that gradually changes the thickness. The position of the space 21 is also not particularly limited, but is preferably a portion near the coupling and fixing means 18 and a radial portion of the two members 2 and 19 to be connected, which are radially inward. It is preferable.

It should be noted that the above-mentioned embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the fixing with the screw 18 was mainly described, but the present invention can be applied to a fixing structure such as spot fixing with an adhesive or spot welding. The space 21 is not particularly limited to the rotor 2 side, and may be formed on the yoke 19 side if necessary.

With the above-described configuration, the coupling relationship between the rotor and the yoke can be maintained without deviating as follows. First, at the time of assembling a product, the rotor 2 and the yoke 19 as shown in FIG. However, when the environmental temperature changes, for example, when the temperature becomes considerably lower than that during balance adjustment, the rotor 2 relatively contracts and the yoke 19 is tightened. However, since there is a space 21 near the connecting and fixing means 18 of the rotor 2 and the yoke 19, no stress is generated in this portion because the rotor 2 does not directly contact the yoke 19. The contact between the yoke 19 and the rotor 2 is at a terminal A of the space 21 axially farther away from the coupling and fixing means 18, that is, at a position where the coupling relationship between the rotor 2 and the yoke 19 is displaced and / or at a position far away from the direction. Occur. Therefore, although the distortion is different depending on the strength relationship between the rotor 2 and the yoke 19, the portion A of the yoke 19 distorts and absorbs the stress, or the portion B on the rotor 2 side where the space 21 is provided distorts and absorbs the stress. It is possible to absorb and apply a stress larger than the tightening frictional resistance of the joint portion J to the joint portion, that is, to shift the joint relationship between the two members [see (B) of FIG. 3]. Therefore, thereafter, when the operating environment temperature returns to its original value, such as when the product is used, the rotor 2 swells and restores the same state as the balance adjustment shown in FIG. 3A [see FIG. 3C].

[0018]

[Effect of device]

 As is apparent from the above description, the present invention is configured to form a space near the coupling and fixing means in the coupling member in which two or more members having different linear expansion coefficients are partially coupled and fixed by the coupling and fixing means. Therefore, even if a different linear expansion occurs between the two members due to a change in the ambient temperature, the space near the coupling and fixing means is deformed so as to relatively invade the other member and the linear expansion coefficient of The amount of displacement corresponding to the difference is absorbed to prevent stress from being generated between the members that are connected and fixed in a spot and have different linear expansion coefficients. Therefore, the coupling and fixing relationship between the members will not be displaced, and the rotating balance will not be disturbed.

[Brief description of drawings]

FIG. 1 is a vertical half sectional view showing an embodiment of a polygon mirror motor to which the present invention is applied.

2 is a cross-sectional view of a space portion of a rotor used in the polygon mirror motor of FIG.

FIG. 3 is an explanatory view showing exaggeratedly the change of the connection relationship at the time of thermal expansion / contraction of the connecting member of the present invention, (A) shows the balance adjustment completed state during product assembly, (B) shows the ambient temperature. The deformation state of the two members when the temperature is lowered, and (C) shows the bonding relationship when the environmental temperature is returned to the original state.

4A and 4B are explanatory views showing changes in the coupling relationship during thermal expansion / contraction in the conventional coupling structure, where FIG. 4A is a balance adjustment completed state during product assembly, and FIG. An unbalanced state is shown, and (C) shows an unbalanced remaining state when the environmental temperature returns to the original state.

FIG. 5 is a vertical half sectional view showing an example of a polygon mirror motor having a conventional coupling structure.

[Explanation of symbols]

 2 rotor 18 which is one of coupling members, screw 19 which is a coupling and fixing means, yoke 21 which is one of coupling members, space

Claims (1)

[Scope of utility model registration request] 1. In a coupling member in which two or more members having different linear expansion coefficients are partially coupled and fixed by a coupling and fixing means, a space is interposed between the two or more members in the vicinity of the coupling and fixing means. A coupling member characterized by the above.